I asked the question to Labs as well on his blasterBoardas well.
Why not using a EPLD to be able to decode any port and then, emulate more sound cards ?
I don't see audio amplification component, how this is done ?

I saw in a 8 bit gui video that only 2 games support it, so why doing it ?

i`m really interested into the software part, a opensource sid emulation core for stm32 would be really great 😀

Well, as mentioned before, the synthesizer part of the emulation core already exists and the author has apparently published it under GPL 3 license: STM32-SID-PLAYER.
Adding bus interfacing code to turn it into a complete SID replacement should be relatively easy.

Why not using a EPLD to be able to decode any port and then, emulate more sound cards ?
I don't see audio amplification component, how this is done ?

I saw in a 8 bit gui video that only 2 games support it, so why doing it ?

The answer is simple:
Firstly, I'd have to buy or improvise a programmer for EPLDs, because I don't currently have one and secondly, the range of supported ports is already broad enough for at least emulation of the lo-tech Tandy card at 2c0h or 2e0h, for which game patches already exist, and for the Covox Sound Master at 280h or 2a0h, albeit without DMA support.
The CMS/Gameblaster port ranges can be made available either by extending the jumper bank or by temporarily using a test lead. Probably the latter, because I want to keep the visual appearance.

Why do it?
This card will serve not only as an SSI-2001 replica, but also as a test bed for multiple things at once, namely:

What could become the first fully open source SID replacement (see above)

An NE558 quad timer replacement consisting of two NE556 dual timers

Potentially other emulation cores (see above)

S/PDIF bitbanging using the STM32's SPI interface via DMA, effectively writing one byte per encoded bit (only if I find time for that)

Condensing all of that into a single PCB layout can reduce the cost, substantially.

Incidentally: Would someone be willing to take part in an order of ~10 PCBs for the Renovation 2001, which is up on github? I could be persuaded to order PCBs, Mouser parts and NE558s. For the SID: people need to supply their own SID, or optionally I would try to get ahold of some SwinSIDs (~15-20 EUR per piece). They seem to be rare at the moment as well.

Incidentally: Would someone be willing to take part in an order of ~10 PCBs for the Renovation 2001, which is up on github? I could be persuaded to order PCBs, Mouser parts and NE558s. For the SID: people need to supply their own SID, or optionally I would try to get ahold of some SwinSIDs (~15-20 EUR per piece). They seem to be rare at the moment as well.

I'd be interested! 😜
And IIRC, all components except for the RCA jack, the tiny NE556s and the bracket are also available from Reichelt and cheaper there.

So I take it you downloaded the files and are impressed?
Keep in mind that the design is still preliminary. There might be errors that I simply don't see.

Incidentally: Would someone be willing to take part in an order of ~10 PCBs for the Renovation 2001, which is up on github? I could be persuaded to order PCBs, Mouser parts and NE558s. For the SID: people need to supply their own SID, or optionally I would try to get ahold of some SwinSIDs (~15-20 EUR per piece). They seem to be rare at the moment as well.

I'd be interested! 😜
And IIRC, all components except for the RCA jack, the tiny NE556s and the bracket are also available from Reichelt and cheaper there.

So I take it you downloaded the files and are impressed?
Keep in mind that the design is still preliminary. There might be errors that I simply don't see.

Then I would suggest to make a smaller order: 3 PCBs at Aisler; because the SIDs will be expensive. The RCA jacks will have to be found (where?) and the 558 -- which we could leave out for the time being, since it would be a beta test. So you never built the card?

Then I would suggest to make a smaller order: 3 PCBs at Aisler; because the SIDs will be expensive. The RCA jacks will have to be found (where?) and the 558 -- which we could leave out for the time being, since it would be a beta test. So you never built the card?

The RCA jacks, NE556 in SSOP14 package and the Keystone bracket are available from e.g. Mouser, probably Digikey, as well.

No, so far, I have never built the card. I published the design as soon as it looked presentable.
However, I am reasonably confident that the MOS6581+NE558 configuration is identical to the original card, because all the visible traces are identical and the schematic makes sense.

MOS8580 configuration should also work, as far as the layout is concerned, but I'm not entirely sure about the values of the resistors that set the voltage of the adjustable voltage regulator.
The problem with these 3-pin adjustable regulators is that the output voltage can drift depending on the load and how much it drifts depends on how large or small the resistor values are.

When it comes to the STM32-based version, some resistor values are still unknown, because their purpose is fine tuning of the card's output levels.

For the time being, I would suggest to wait with PCB orders and to take another close look at the schematics and layout to compare them to existing board photos.

So far, I have only found one minor error:
The position of the mounting holes for the bracket was off by fractions of a millimeter. Just enough to prevent it from fitting.

Other than that, I have added a hidden pad to simplify Fagear's compatibility mod for fast ISA busses, which is not included in my board layout.
You still have to cut a trace and run a wire, just like you would have had to do on the original card, but the added pad allows you to hide the wire below a chip.

Mmh... I'd have to shift the DA15 socket by 7 or 8 mm, i.e. almost to the edge of the board.
A configuration without joystick port would need both mounting holes for the bracket, though.
This repositioning would also be among the most noticeable alterations to the design.

In short: I understand the motivation, but I'm not particularly fond of the idea because of the visible alterations it implies.
The choice of a cheaper and more common type of DA15 socket was a compromise, already, and based on the realization that of the two DA15 variants on the original cards, only the ill-fitting one is still available and even that is ten times as expensive.

I spotted an error in the schematic: The values for the LM1117-ADJ's configuration resistors were way off.
I must have forgotten to set the reference voltage in KiCAD's voltage regulator calculator.
The updated version is online and the board layout stays the same, anyway.
Everything else looks good, so far.

If everything goes well, I'm going to order a batch of boards in a couple of days.
A ten-piece batch would result in ~5€ per board.